Researchers wanted to determine if there was an association between daily applea
ID: 3365350 • Letter: R
Question
Researchers wanted to determine if there was an association between daily
appleapple
consumption and the occurrence of
breast cancerbreast cancer.
The researchers looked at
94 comma 55994,559
women and asked them to report their
appleapple-eatingeating
habits. The researchers also determined which of the women had
IDC breast cancerIDC breast cancer.
After their analysis, the researchers concluded that consumption of
two or more servingstwo or more servings
of
Granny Smith applesGranny Smith apples
per day was associated with a reduction in
IDC breast cancerIDC breast cancer.
Complete parts (a) through (c) below.
(a) What type of observational study was this? Explain.
A.
This was a cohort study because it identified a group of individuals to participate in the study and observed the group over a long period of time.
B.
This was a cross-sectional study because all information about the individuals was collected at a specific point in time.
C.
This was a case-control study because individuals that had a certain characteristic were matched with those that did not.
(b) What is the response variable in the study? Is the response variable qualitative or quantitative? What is the explanatory variable?
What is the response variable in the study? Is the response variable qualitative or quantitative?
A.
The response variable is the number of individuals who participate in the study who
eateat
two or more servingstwo or more servings
of
Granny Smith applesGranny Smith apples
per day. The response variable is quantitative.
B.
The response variable is consumption of
Granny Smith applesGranny Smith apples.
The response variable is quantitative.
C.
The response variable is whether the woman has
IDC breast cancerIDC breast cancer
or not. The response variable is qualitative.
D.
The response variable is the number of individuals who participate in the study. The response variable is quantitative.
What is the explanatory variable?
A.
The explanatory variable is the number of individuals who participate in the study.
B.
The explanatory variable is the number of individuals who participate in the study who
eateat
two or more servingstwo or more servings
of
Granny Smith applesGranny Smith apples
per day.
C.
The explanatory variable is consumption of
Granny Smith applesGranny Smith apples.
D.
The explanatory variable is whether the woman has
IDC breast cancerIDC breast cancer
or not.(c) In their report, the researchers stated that "After adjusting for various demographic and lifestyle variables, daily consumption of
two or more servingstwo or more servings
was associated with a 30% reduced prevalence of
IDC breast cancerIDC breast cancer."
Why was it important to adjust for these variables?
A.
The researchers may be concerned with confounding that occurs when the effects of two or more explanatory variables are not separated or when there are some explanatory variables that were not considered in a study, but that affect the value of the response variable.
B.
The researchers wanted to ensure that the sample was large enough in order to perform inference.
C.
The researchers wanted to ensure that the study was representative of the entire population, so they were likely to adjust the responses to match actual data collected for the entire population.
D.
The researchers were sure that various demographic and lifestyle variables had greater influence than daily consumption of
two or more servingstwo or more servings.
Explanation / Answer
a) B.This was a cross-sectional study because all information about the individuals was collected at a specific point in time.
b) C.The response variable is whether the woman has IDC breast cancerIDC breast cancer or not. The response variable is qualitative.
C.The explanatory variable is consumption of Granny Smith apples.
c) A.The researchers may be concerned with confounding that occurs when the effects of two or more explanatory variables are not separated or when there are some explanatory variables that were not considered in a study, but that affect the value of the response variable.
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